JB: One night, when it was clear that the odds weren’t good, he asked me to stay after dinner at his house, about a mile from here. He said: “Dad, I know you love me more than anyone in the world. But promise me you’ll be O.K. I’ll be O.K., Dad.” He had come face to face with his mortality. He watched me go through the loss of his mother and sister. And he didn’t want me to turn inward. He didn’t want me to give up on the robustness of life.

PG: You were reluctant to confide in President Obama about Beau.

JB: It was complex. I didn’t want him to carry the burden of feeling sorry for me. Several times, when we talked about Beau, he started sobbing, and I had to console him. I didn’t want to put him through that, not with all the responsibility he had on his back.